How to implement one object moving towards another

So im working on a game in which there is a sphere centerd in (0, 0, 0) i got another spheres made around it, and go towards the object, how can i implement it?
Is ther a way to create object that gravitate other object?

Can anyone help me with a smiple sript, getting public gameObject(or Transform) and pulling the object the script atouched to the referenced object? in C# please, thanks!!!

In Unity, go to the menu: Assets → Import Package → Scripts. There is a “SmoothFollow” script for you. Or you can use this:

using UnityEngine;
using System.Collections;

public class FollowTarget: MonoBehaviour {

	public GameObject target;
	// Update is called once per frame
	void Update () {
        if (target != null) {	
	        this.transform.LookAt( target.transform );
            this.transform.position = Vector3.Lerp( transform.position, target.transform.position, Time.deltaTime );